GB2180206A

GB2180206A - Motor vehicle steering assembly

Info

Publication number: GB2180206A
Application number: GB08621906A
Authority: GB
Inventors: Yutaka Tashiro; Shoichi Sano
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1985-09-11
Filing date: 1986-09-11
Publication date: 1987-03-25
Also published as: US4709936A; FR2586989B1; GB2180206B; DE3630984A1; GB8621906D0; FR2586989A1; DE3630984C2

Description

1 GB 2 180 206 A 1

SPECIFICATION

Steering assemblyfor motor vehicle 1 10 The present invention relates to a steering assembly for use in a motor vehicle, and more particularlyto a rear wheel steering assembly for use in a motor vehicle having steerable front and rear wheels.

Recently, some motorvehicies are equipped with a system for steering rear wheels as well as front wheels. In general, such a front and rearwheel steering system includes, in addition to a conventional frontwheel steering assembly, a similar rearwheel steering assembly comprising rearwheel steering components such as knuckle arms and tie rodswhich are operatively coupled to a steering wheel and associated with rear suspension mechanisms.

Because of these additional rearwheel steering components required to steerthe rearwheels, the number of parts mounted on a rear vehicle frame portion and operatively associated with the rear wheels is increased.

Viewed from one aspectthe present invention pro- vides a steering mechanism in a motorvehicle, comprising:

a trailing arm pivotally supported on a pivotshaft extending substantially transversely of the motor vehicle and rotatably supporting a wheel at a rear endthereof; first, second, and third links respectively having one end pivotally coupled to saidtrailing arm and extending substantially transversely of the motorvehicle; a steering gear boxforsteering the wheel; and said first link having its otherend operatively coupled to said steering gear box.

In a preferred form of the invention n which the said wheel is a rear wheel of the vehicle, two of the three links are coupled byjoints to the trailing arm at a front end thereof and the other end mounted in the rear steering gear box. Preferably, the steering assembly includes a holder having a lower end by which the said pivot shaft is pivotally supported and an upper end swingably supported on a second pivot shaft extending substantially longitudinally of the vehicle frame so that the trailing arm can be angularly moved transversely.

In such a preferred three-link trailing arm assembly, since the link on the front end of thetrailing arm is operatively coupled to the rear steering gear box, this link can double as a rearwheel steering tie rod for enabling the trailing arm to be angularly moved transversely about the second pivot shaft, so thatthe trailing arm can function as a knuckle arm for steering the rearwheel. Thejoints by which thetwo links are coupled to the trailing arm nearthe steering center of the rearwheel jointly serve as a kingpin axis aboutwhich the rear wheel is steerabie. The link or steering tie rod on the front end of the trailing arm is widely spaced from the kingpin axis, so that the lever ratio may be large, and thus tolerances of the gear box and the steering tie rod link may also be large. A fuel tank or other parts may easily be installed in a relatively large space defined between the steering tie rod link and the two links coupled by the joints to thetrailing arm.

Two embodiments of the invention will nowbe described bywayof example and with referencetothe accompanying drawings, in which:

Figure 1 is a perspectiveview of a steering assembly of the present invention, which is incorporated in a rear-wheel-drive motorvehicle; Figure2 is an enlarged perspective view of the steering assembly associated with a rearwheel suspension; and Figure 3 is a perspective view of the steering assembly incorporated in a non-rear-wheel-drive motorvehicle.

Figure 1 shows a front and rearwheel steering system including a rearwheel steering assembly according to the present invention.

A steering wheel 1 is coupled to a steering shaft 2 operatively joined by a universal joint 3 to a rack-and- pinion-type front steering gear box 4 having a rack shaft 5 with its opposite ends connected to two tie rods 6, respectively. The tie rods 6 are operatively connected to respective knuckle arms 8 on which frontwheels 7 are rotatably mounted.

Afront pinion shaft 9 meshing with the rackshaft 5 projects rearwardly from the front steering gear box 4 and is coupled by a front universal joint 11 to a linkage shaft 12, which in turn is coupled by a rear universal joint 13 to a rear pinion shaft 14 operatively coupled to a rear steering gear box 15.

As illustrated in Figures 1 and 2, each of two rear suspensions includes a trailing arm 21 extending substantially longitudinally of a vehicle frame. The trailing arm 21 comprises a plate 22 formed prefer- ably by pressing and extending in a vertical plane and a reinforcing plate 23 joined to plate 22 over its recessed surfaceto provide a rigid body. A knuckle 25 is securely coupled bytwo vertically spaced bolts 26 to the rear end of the trailing arm 21. A rubber bushing 27 with a tube is mounted on the trailing arm 21 near its front end, the tube of the rubber bushing 27 having an axis extending substantialiytransversely of the vehicle frame. A pivotshaft 28 is inserted through thetube of the rubber bushing 27, and supported by a holder45 having two laterallyspaced depending members 46. The depending members46 havefront and rear portions spaced from each other and are interconnected bytwo spaced tubular members 47which are concentricwith each other. Rubber bushings 48with tubes arefixediy mounted in the tubular members 47 respectively. The rubber bushing 27 on the trailing arm 21 is positioned between the depending members 46 of the hoider45, and the pivot shaft 28 is supported on the depending mem- bers 46 so that the trailing arm 21 is pivotally mounted on the holder 45.

Three lateral links 31, 32,33 extending substantially transversely of the vehicle frame are coupled to the trailing arm 21. The first lateral link 31 has an outer end coupled by a ball joint 34 to the front end of an extension 24 of the trailing arm 21 which extends forwardly of the rubber bushing 27. The second and third lateral links 32,33 have outer ends coupled by ball joints 35,36, respectively, to the knuckle 25 at its upper and lower ends, respectively.

2 GB 2 180 206 A 2 An axle 38 connected to a drive shaft 37 is rotatably supported on the knuckle 25 and projects outwardly from the knuckle 25. A rearwheel 39 is mounted on the axle 38. A damper41 has a lower end connected by a support pin 43 through a forked member 42 to the third lateral link 33 near an outer end thereof. The drive shaft 37 extends through the forked member 42.

For assembling each of the trailing arms 21 on the vehicle frame, the inner ends of the second and third lateral links 32,33 are pivotally supported on brackets 55,56 of the vehicle frame respectively by rubber bushings 52,53 with tubes, and then a pivot shaft having an axis M extending substantially long- itudinally of thevehicleframe is inserted through the tubes of the rubber bushings 48 in thetubular mem bers 47 of the holder45 and is connected to respect ive brackets 49 of the vehicle frame. The upperend of thedamper41 is joined to the vehicle frame.

Then, the inner ends of the first lateral links31 85 coupled to the front ends of the trailing arms 21 are inserted into the rear steering gearbox 15 and oper atively coupled as by joints to the opposite ends of a rack shaft (not shown) which is held in meshwiththe rear pinion shaft 14.

As described above, the pivotshaft 28 on the trail ing arm 21 issupported bythe holder45which is pivotally supported bythe longitudinal pivotshafton the vehicle frame. Therefore, transverse movement of thetraffing arm 21 dueto swinging movementof the lateral links 31,32,33 atthetimethe rearwheels 39 bounds and rebounds isfacilitated by movement ofthe pivotshaft28 caused byswinging movement of the holder45 aboutthe axis M of the longitudinal pivotshaft.

In the th ree-iink trailing arm assembly constructed as above, which serves as a rear suspension, the innerend ofthefirst lateral link31 coupledtothe front extension 24 of the trailing arm 21 is operatively coupled to the rear steering gear box 15. Therefore, 105 when the steering wheel 1 is turned to induce trans verse movement of the f irst latera 1 link 31, the trailing arm 21 can be moved transversely aboutthe axis M of the long itudinal pivot shaftthat is located rea rwa rdly of the f irst lateral link31. Therefore, the rear wheels 39 can be steered with the front wheels 7 in response to tu rning movement of the steering wheel 1.

Inasmuch as the f irst lateral link 31 serves as a rear wheel steering tie rod and the trail ing arm 21 serves as a knuckle arm, the nurn ber of components assoc iated with the rear wheel 39 is not increased to pro vide the assern bly for steering the rea rwheel 39.

The bal 1 joints 35,36 by which the second and third lateral 1 inks 32,33 positioned above and below the trailing arm 21 are cou pled to the knuckle 25 jointly provide a kingpin axis K extending along a straight line connecting these bail joints 35, 36 for steering the rear wheel 29. Si nce the f irst lateral link 31 posi tioned most remotely from the king pin axis K serves 125 as the rear wheel steering tie rod, the lever ratio is large, and the rear gear box 15 and the tie rod link 31 can be manufactured with relatively low dimensional accuracy.

The space between the f irst lateral 1 ink 31 and the 130 second and third lateral 1 inks 32,33 is relatively la rge since the f irst lateral 1 ink 31 is positioned at the f ront end of the trailing arm 21 and the second and third lateral links 32,33 are positioned atthe rear end of the trailing arm 21. Afuel tank or other components can easily be installed in such a large space.

A rearwheel steering assembly of the present invention can also be incorporated in a motorvehicie which is not of the rear-wheel-drive type. More speci- fically, as shown in Figure 3, an axle 29 is fixed to the knuckle 25 on the rear end of each of the trailing arms 21, and the rearwheel 39 is idly rotatably mounted on the axle 29. The other structural details are the same as those shown in Figure 1.

One advantage of a steering mechanism according to the present invention is thatthe number of parts operatively associated with a rearwheel is reduced, thereby providing a relatively large rearspacewhich can effectively be utilized for installation of a fuel tank orother components.

It isto be clearly understood thatthere are no particularfeatures of the foregoing specification, orof any claims appended hereto, which are at present regarded as being essential to the performance of the present invention, and that any one or more of such features or combinations thereof maytherefore be included in, added to, omitted from or deleted from any of such claims if and when amended during the prosecution of this application or in the filling or pro- secution of any divisional application based thereon.

Claims

1. A steering assembly in a motor vehicle, com- prising; a trailing arm pivotally supported on a pivot shaft extending substantially transversely of the motor vehicle and rotatably supporting a wheel at a rear endthereof; first, second, and third links respectively having one end pivotally coupled to said trailing arm and extending substantially transversely of the motorvehicle; a steering gear boxforsteering thewheel; and said first link having its other end operatively coupled to said steering gear box.

2. A steering assembly according to claim 1, wherein said second and third links have their other ends pivotally supported on a vehicle frame of the motor vehicle and are coupled to said trailing arm in the vicinity of a steering center about which said wheel is steerable.

3. A steering assembly according to claim 2, wherein said second link is coupled to an upper por- tion of said trailing arm at said rear end thereof and said third link is coupled to a lower portion of said trailing arm at said rear end.

4. A steering assembly according to claim 3, wherein said one end of said second and third links are coupled to said trailing arm by respective joints interconnected by a straight line serving as a kingpin axis for steering said wheel.

5. A steering assembly according to claim 4, further including a damper having one end pivotally mounted on said third link near the joint by which 3 GB 2 180 206 A 3 said third link is coupled to said trailing arm.

6. A steering assembly according to claim 5, further including a drive shaft for driving said wheel, said drive shaft extending between said second and third links and coupled to said wheel through the rear 70 end of said trailing arm.

7. A steering assembly according to any preced ing claim, further including a holder having a lower end on which said pivot shaft is pivotally supported and an upper end pivotally supported on a second pivot shaft extending substantially longitudinally of the motor vehicle so that said trailing arm can be an gularly moved substantially transversely of the motor vehicle through said holder.

8. A steering assembly according to claim 7, further including a vehicle frame, said second pivot shaft being mounted on said vehicle frame, said second and third links having their other ends pivot ally supported on said vehicle frame.

9. A steering assembly according to claims 5 and 8, wherein the other end of said damper is pivotally supported on said vehicle frame.

10. A steering system in a motor vehicle, com prising; avehicleframe; a steering shaft mounted on a front portion of said vehicleframe; a front steering gear boxto which a lowerend of the said steering shaft is operatively coupled; a linkage shaft extending substantially longitudin ally of the motorvehicle and having one end oper atively coupled to said front steering gear box; a rear steering gear boxto which the other end of said linkage shaft is operatively coupled; a trailing arm pivotally supported on a pivotshaft extending substantially transversely of the motor vehicle and rotatably supporting a wheel at a rear endthereof; first, second, and third links each having one end pivotally coupled to said trailing arm and extending substantiallytransverseiy of the motorvehicle; and said first link having its otherend operatively coupled to said rear steering gear box.

11. A steering system according to claim 10, wherein said second and third links have their other ends pivotally supported on said vehicle frame and are coupled to said trailing arm in the vicinity of a steering center about which said wheel is steerable.

12. A steering system according to claim 11, wherein said second link is coupled to an upper por tion of said trailing arm at said rear end thereof and said third link is coupled to a lower portion of said trailing arm at said rear end.

13. A steering system according to claim 12, wherein the said one end of said second and third links are coupled to said trailing arm by respective joints interconnected by a straight line serving as a kingpin axis for steering said wheel.

14. A steering system according to claim 13, further including a damper having one end pivotally mounted on said third link nearthe joint by which said third link is coupled to said trailing arm.

15. A steering system according to claim 14, further including a drive shaft for driving said wheel, said drive shaft extending between said second and third links and coupled to said wheel through the rear end of said trailing arm.

16. A steering system according to any of claims 10 to 15, further including: a holder having a lower end on which said pivot shaft is pivotally supported and an upper end pivotally supported on a seond pivot shaft extending substantially longitudinally of the motor vehicle so that said trailing arm can be angu larly moved substantially transversely of the 75 motorvehicle through said holder.

17. A steering system according to claim 16, wherein said second pivot shaft is mounted on said vehicle frame, said second and third links having their other ends pivotally supported on said vehicle 80 frame.

18. A steering system according to claims 14to 18, wherein the said other end of said damper is pivotally supported on said vehicle frame.

19. Apparatus according to any preceding claim, 85 wherein the said wheel is a rear wheel.

20. A steering system in a motor vehicle, su bstantial ly as herein before described with reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by Croydon Printing Company (1) K) Ltd,2187, D8817356. Published by The Patent Office, 25 Southampton Buildings, London WC2A 'I AY, from which copies may be obtained.